From the Guidelines
Secondary spontaneous bacterial peritonitis (SBP) prophylaxis should be initiated in cirrhotic patients who have had a previous episode of SBP, with the recommended regimen being norfloxacin 400 mg orally once daily or trimethoprim-sulfamethoxazole (TMP-SMX) double-strength tablet once daily as an alternative, as supported by the most recent and highest quality study 1. The rationale for secondary prophylaxis is that patients who have had one episode of SBP have a 70% chance of recurrence within one year without prophylaxis, as noted in 1.
Key Laboratory Criteria for Monitoring
Some key laboratory criteria that should be monitored during prophylaxis include:
- Complete blood count to assess for neutropenia (a potential side effect of antibiotics)
- Renal function tests (BUN, creatinine) to monitor kidney function
- Liver function tests to track the progression of liver disease Additionally, ascitic fluid analysis should be performed if symptoms of SBP recur, looking for neutrophil count >250 cells/mm³, which indicates infection, as stated in 1.
Prophylaxis Duration and Rationale
Prophylaxis should be continued indefinitely or until liver transplantation or resolution of ascites, as the risk of recurrence remains high without prophylaxis, and antibiotic prophylaxis works by suppressing gut flora, particularly gram-negative bacteria, which are the most common causative organisms in SBP, as discussed in 1. Some alternative options, such as ciprofloxacin 500 mg orally once daily, can also be used if the other options are unavailable, but the effectiveness of quinolones in patients with MDRO or organisms other than gram-negatives is uncertain, as noted in 1.
From the Research
Secondary SBP Prophylaxis Labs Criteria
The following lab criteria are relevant for secondary SBP prophylaxis:
- Ascitic fluid protein ≤1.5 g/dL 2, 3
- Ascitic polymorphonucleated cell count <250/mm3 2
- Presence of history of SBP 2, 4, 3, 5, 6
- Child-Pugh score ≥9 points 3
- Serum bilirubin ≥3 mg/dl 3
- Impaired renal function 3
Antibiotic Prophylaxis
The use of antibiotic prophylaxis for secondary SBP prevention is supported by the following studies:
- Norfloxacin 400 mg daily is effective for secondary prophylaxis 2, 4, 5, 6
- Rifaximin 550 mg twice daily is more effective than norfloxacin for secondary prophylaxis 3
- Trimethoprim-sulfamethoxazole has similar efficacy to norfloxacin for primary and secondary prophylaxis, but is associated with an increased risk of adverse events 4
- Ciprofloxacin once weekly is not inferior to norfloxacin once daily for secondary prophylaxis 2, 4